Quiz

QUIZ

1. What is work in physics essentially the same thing as?

a. Power b. Change in energy c. Displacement d. Force

Answer: b. Work involves any of these things but is essentially the same thing as a change in energy, which does involve forces, movement, and displacement, but is not the same thing as these things. Power is related to work but is not the same thing.

2. How is work related to force?

a. Work is equivalent to force over a period of time. b. Work is equivalent to force multiplied by a specific constant. c. Work is equivalent to force multiplied by the distance it acts on. d. Work is equivalent to potential energy multiplied by force.

Answer: c. Work is proportional to force but it is only that component of force that is acted upon over a certain distance.

3. In the equation in which work is equal to the Force times distance times the cosine of theta, what does theta represent?

a. The angle between the normal weight and the horizontal direction. b. The angle between the force vector and the displacement vector. c. The angle between a pulley system vector and the applied force on the system. d. The angle between the force vector and the y-axis.

Answer: b. This is actually very simple. When doing work equations, you take the magnitude of the force vector times the magnitude of the direction/displacement vector and the cosine of the angle theta, which is the angle between them in degrees.

4. What is the proportionality associated with kinetic energy and the velocity of a body in motion?

a. Kinetic energy is directly proportional to velocity b. Kinetic energy is proportional to the square root of velocity c. Kinetic energy is proportional to the square of velocity d. Kinetic energy is inversely proportional to velocity

Answer: c. Translational kinetic energy is one-half the mass times the velocity squared so it is proportional to the square of the velocity.

5. How does the velocity of something relate to its mass and height as it falls?

a. The velocity is proportional to its mass and its height b. The velocity is proportional to its mass and the square root of its height c. The velocity is proportional to just the height d. The velocity is proportional to the square root of its height but not the mass

Answer: d. In the equation where something falls, you need to put together the kinetic energy and potential energy equations, which cancel out the mass so this is not a factor at all. This leaves the fact that height and the force of gravity equals one-half the velocity squared or the velocity is the square root of 2 times the height.

6. You lift an object up an incline of ten meters to one-meter total height versus lifting up one meter by hand without the benefit of a ramp. What is the difference in the object’s potential energy in each situation?

a. The potential energy of raising the object is a tenth the potential energy of the ramp situation. b. The potential energy of each situation will be the same. c. The potential energy of raising the object is ten times the potential energy of the ramp situation. d. The potential energy of raising the object is one-one hundredth the potential energy of the ramp situation.

Answer: b. The potential energy of the object is directly related to its overall height and does not depend on the path that is taken.

7. When looking at the potential energy of a spring, what is it related to?

a. It is proportional to the distance the spring is compressed. b. It is proportional to the square of the distance the spring is compressed. c. It is proportional to the cube of the distance the spring is compressed. d. It is the same, regardless of the spring and is proportional to the square of the distance the spring is compressed.

Answer: b. The equation for the potential energy is one-half times the force constant times the distance compressed squared. This force constant is not the same for every spring so there is a force constant involved that depends on the spring.

8. When considering the conservation of mechanical energy, what factor least destroys this concept?

a. The thermal energy of the system b. Frictional forces of the system c. Air resistance forces d. Gravitational forces on a system

Answer: d. Gravitational force is a conservative force so it follows the rule of conservation of mechanical energy. Things like air resistance, frictional forces, and thermal energy will take energy away from mechanical energy and cannot be turned into work, destroying the concept of conservation of conservative forces. In reality, it is difficult to find a real system that has true conservation of mechanical energy.

9. What type of energy gets transformed into what other type of energy in the act of photosynthesis?

a. Thermal energy into chemical energy b. Radiant energy into chemical energy c. Chemical energy into kinetic energy d. Radian energy into thermal energy

Answer: b. Radiant energy gets turned into chemical energy in the act of photosynthesis. This is the process of sunlight creating molecules that ultimately store chemical energy through their chemical bonds.

10. The efficiency of an energetic system is defined as what?

a. The percent of work output divided by energy input of the system b. The sum of all the energy inputs in a system c. The energy input divided by the work output of the system d. The sum of the energy output minus the energy input

Answer: a. The efficiency of the energetic system is defined by percentages. It is the percent of the work output divided by the energy input of the system. It is a maximum of 100 percent but is actually much less than this in many energetic systems.